/Engine/Plugins/Runtime/MeshModelingToolset/Source/MeshModelingTools/Public/EditMeshPolygonsTool.h
Flip normals and face orientation for the current set of selected faces
[UFUNCTION](Programming/UnrealArchitecture/Reference/Functions)(CallInEditor, Category=TriangleEdits, Meta=(DisplayName="Flip", DisplayPriority=7)) void Flip()